In recent years, the average life expectancy has been increasing to thereby increase the elderly population because of the advances in medicine and science. However, the change in dietary habits or living environments and the environmental pollution have increased, and new illness and infectious diseases due to viruses or fungi have appeared, so that anxiety to the health of the people has been increasing. Particularly, in the so-called advanced nations, the increase of patients of life-style related diseases such as diabetes mellitus, hypertension or the like has become a problem.
On the other hand, since the number of medical institutions has not so increased as to cope with such increase of patients, and since there are communities where there is no medical institution which patients can attend, there is a concern for how to cope therewith, also from the viewpoint of public policy.
Description will be made below with reference to a specific example. Of the diabetes mellitus patients who are increasing at present, the so-called insulin-dependent type (type I) diabetes mellitus patients have no secretion of insulin from their pancreas and need to be regularly administered with insulin. Because insulin is administered by subcutaneous injection at present, the physical and mental labor of patients is large.
In order to reduce the labor of such users, a pen-shaped injection syringe has been developed which has a thin needle and gives less pain to a patient. However, because most of the I-type diabetes mellitus patients work as with an able-bodied person except for requiring regular administration of insulin. Therefore, they have mental resistance to injection in public even with a pen-shaped injection syringe, so that it is difficult to administer insulin at a proper time. As a result, with such a method, there is a possibility that the users may not be treated appropriately.
On the other hand, a treatment for a user in which a drug ejection device for allowing the user to intake the drug through inhalation is utilized in combination with information database such as electronic medical records is being embodied. Such a drug ejection device also serves as a personal digital assistant that is provided with both a storage means for storing information related to an individual user including information on the medical record and prescription of the user and an inhaler for ejecting the drug in the form of fine liquid droplets to allow the user to inhale the drug. Further, the drug ejection device includes, in order for the user to inhale the drug according to the information of the prescription, an ejection control means for controlling, based on an inhalation profile, the inhaler to eject the drug (refer to International Publication Nos. WO 95/01137 and WO 02/04043).
Such a drug ejection device can accurately manage the dose and frequency of administration of the drug according to the prescription, performs appropriate ejection control in accordance with the inhalation profile of an individual user, and can effectively administer the drug. According to such a drug ejection device, since it is not required to use a conventional medical instrument such as an injection syringe when administering the drug, it is possible not only to easily operate the device without expert knowledge, but also to diminish the pain by a needle of an injection syringe of a user.
Meanwhile, appropriate means for dealing with an operation failure of a drug ejection unit or the like is in demand. For example, in a case where a user has a chronic disease and requires regular administration of a drug, the administration and management of the drug depends on the reliability of the drug ejection device and the appropriate operation by the user. In this case, there is a need for provision of a function of somehow notifying the user of an operational failure of the device including a drug ejection unit, a physical attachment error of a consumable part, or the like.
Further, even in a case where the drug ejection unit in the drug ejection device is attached normally, when it is necessary for the user to bring the drug ejection device with him, there is a possibility of causing ejection failure due to battery exhaustion or the like. Still further, it is known that in order to obtain, through inhalation of liquid droplets of insulin from a drug ejection device, the same effect as that obtained when administering insulin to a human body through injection, ejection of liquid droplets with a particle diameter of about 3 μm is required. Accordingly, the size of an ejection orifice is necessarily reduced, thereby posing a possibility of ejection failure due to clogging of the ejection orifice.
Therefore, there has been proposed, as means for resolving the problem of such ejection failure, a method of performing preejection of liquid droplets before inhalation to improve the ejection reliability (see Japanese Patent Application Laid-Open No. 2004-97617).
However, when performing the preejection before the inhalation, the drug liquid droplets float in an inhalation flow path, so there is a possibility of inhaling the preejected drug and the drug for inhalation together at a time of the inhalation. In some drugs, even a small difference in amount may result in a large difference in the effect thereof, and there are cases where the amount of inhaled drug must be strictly controlled.
Further, since a drug contains much protein, there is a possibility that adherence of protein to an inside wall of an inhalation flow path may result in generation of mold or putrefaction, thereby posing a concern about hygiene. In order to resolve such concern, it is required for users themselves, medical institutions, manufacturers, or the like to perform continuous cleaning, disinfection, or maintenance.